Measuring instrument



Sept. 1, 1942.

L. S. MALM ETAL MEASURING INSTRUMENT Filed Dec. 19, 1941 FiE-J- INVENTORS '5'. MALM I. ONETO M 1 w, r

147'7'0 EYS Patented Sept. 1, 1942 RIEASURING INSTRUMENT Leland S. Malm and John F. Oneto, San Francisco, Calif.

Application December 19, 1941, Serial No. 423,651

8 Claims.

This invention relates to measuring instruments and particularly devices which will be found useful in scaling or estimating drawings, blue prints, maps, and the like.

One of the principal objects of this invention is to provide a measuring or scaling device which will be portable and useful in conjunction with conventional electro-magnetic counting systems.

Another object of the invention is to provide a device of the character described which will be comparatively simple in construction and yet readily adaptable to the various scales employed in the making of drawings, maps, and the like.

Other objects of the invention will become apparent as this specification proceeds.

In the drawing forming a part hereof:

Figure 1 is a longitudinal vertical section through the device embodying the invention;

Figure 2 is a longitudinal horizontal section of the device forming the subject matter of Figure 1;

Figure 3 is a transverse sectional view of the device along the line 3-3 of Figure 2; and

Figure 4 is a longitudinal section through the handle of the device taken along the line 4-4 of Figure 2.

In terms of general inclusion, the preferred form of the invention illustrated herein utilizes a rotatable member or traction wheel which is adapted to be moved over the part of the drawing or map to be scaled, which traction wheel has an operative connection through a train of gears to a switch means adapted to make and break a circuit with an electro-magnetic counting system employed to record the lineal measurement of the drawing or map or objects depicted thereon.

In the form illustrated in the accompanying drawing, we provide an elongated, substantially cylindrical housing Ill for the switch and actuating mechanism therefor, which housing also serves as a handle. A plate extending longitudinally within the housing I serves as a mount II for the actuating mechanism about to be described and a reduced portion-of the plate extends through one end of the housing ID in the form of an arm I2 to support a rotatable traction wheel I3.

Since it is general practice for drawings to be scaled on the order of one-quarter or one-eighth of an inch to the foot, the preferred form of our invention includes a traction wheel I3 having a scale I5 denoting quarters and halves of an inch, as a means of visibly indicating distances traversed by the wheel.

The wheel I3 is rotatably mounted at one side of the end of the arm I2 on a shaft I6 journaled therein (see Figure 2); and on the opposite end of the shaft I6, we provide a bevel gear I'I. Gear I'I meshes with a similar bevel gear I8 on shaft I9 journaled in posts on arm I2; and a third bevel gear 2-I, at the opposite end of shaft I9 meshes with a bevel gear 22. Gear 22 is fixed on a shaft 23 journaled through plate I I and'carrying on its opos ite end a pair of star wheels or ratchets 24 and 25. It is through this train of gears that rotative movement of traction wheel I3 is transmitted eventually to a conventional micro switch, indicated by the numeral I4, to make and break the circuit including a conventional e'lectro-magnetic counting system.

The star wheels or ratchets Hand 25 are fixed on shaft 23 and, according to the number and spacing of the teeth carried thereby, may be selectively used to trip the switch means employed according to the scale of the drawing to be checked; i. e., one-eighth or one-quarter inch to the foot, respectively. While we have illustrated only two such ratchet wheels, it will be understood that, if need arises, additional wheels of this character maybe added with corresponding pawls to adapt the device for varying scales.

A pair of pawls 26 and 21, oppositely arranged on the order of 180, on a druin '28, are adapted to be selectively moved into the path of one or the other of-ratchets 24 or 25. I"he drum 28 is slidably mounted on a pin'29 fixed on disc 30 hearing against plate II. A shaft 31 fixed on the opposite face of disc 39, and in coaxial alignment with the pin-2'9 is 'journaled in plate I I.

A's'will be noted from Figure 3 of the drawing, drum 28 and disc 30 are adapted to be united for conjoint rotative -movement through the provision of pins 32 on the'disc 30, oppositely arranged adjacent the periphery thereof on the order of 180, and registering holes 33 in the inner face of the drum 28. A helical spring 34 within the chamber 35 of 'drum 2B and encircling pin '29, one end of which is anchored in said pin and the other end of which bears against the inner face of the drum 28, normally urges the drum into the above-described connection with disc 30. The outer face of drum 28 has an integral, ax-

ially arranged sleeve 36 projecting therefrom through the handle or housing I0 and a knurled knob 31 is fixedithereon to facilitate the selection between the ratchets 24 and 25 and the proper disposition of the pawls 26 and 21 in operative relation thereto. By pulling knob 31, the drum '28 may be disengaged from disc 30 against the tension of spring 34 and partially rotated to dispose pawl 21 in the path of ratchet 25 or pawl 26 in the path of ratchet 24 and when properly positioned, release of knob 31 will permit spring 34 to again urge drum 28 into engagement with disc 30 since pins 32 will enter registering the holes 33 to interlock the said elements.

The conventional micro-switch I4 is mounted on plate II and has a leaf spring contact 40 projecting therefrom parallel to the plate (See Figure 4.) The switch illustrated is of the normally closed type wherein contact 40 bears against contact 4|, and the opening of the switch a-ctuates the electrical counting mechanism with which it is operatively connected. In the form of the invention illustrated, we employ a squared knob 42 fixed at the end of the shaft 3| to open the above-described contacts. Normally one of the flat sides of knob 42 rests upon the leaf spring 40, as indicated in Figure 4 of the drawing. When shaft 3| is partially rotated or rocked by the tripping of either pawl 26 or 27, the corners of squared knob 42 will act as an eccentric to urge leaf spring contact 40 away from contact 4| and open the circuit. When pawl 26 or 21 has slipped from the teeth of its corresponding ratchet, 24 or 25, respectively, the spring contact 40 will bear against the knob 42 and partially rotate or rock the shaft 3| to reset the pawl and at the same time again contact the member 4| to close the circuit. A stop pin 43 seated in plate projects outwardly to limit the movement of spring contact 49 and hence prevent more than partial rotation of shaft 3|.

It will be understood, of course, that knob 42, shaft 3|, disc 30, and stop pin 43 are all made of nonconductor material as a means of insulating switch 25 from the remainder of the structure.

If desired, the device may be provided with a cover 46 for the gears l6 and I! and the shaft 9 in the form shown in Figure 2. In addition to protecting the operating mechanism from foreign matter and preventing accidents through contact with the moving parts, such cover may be utilized to improve the appearance of the device and, at the same time, provide a structure fully enclosed save for the traction wheel l3 and the knob 31.

To summarize, the operation of the device is as follows:

The operator first determines the scale of the drawing or blueprint to be checked and then sets the instrument accordingly by manipulation of the knob 31. By withdrawing knob 31, drum 28 may be disengaged from disc 30;and upon rotating the knob through 130, pawl 26 may be positioned to contact the teeth of ratchet 24 or pawl 21 to contact ratchet 25, according to whether the scale is one-eighth or one-quarter of an inch to the foot, respectively; and the knob 31 is then released. Spring 34 will then urge drum 28 into engagement with disc 30, thus interconnecting the elements whereby tripping of pawl 26 or 27 will rock shaft 3| to open the contacts 4|) and 4 Thus upon movement of traction wheel l3 over a given surface, the rotative movement thereof will be transmitted through the train of gears I6 and II, the shaft l9, and gears 2| and 22 to the shaft 23 and thence by the ratchet 24 or 25 to pawl 26 or 21, by which a rocking motion will be imparted to shaft 3| to open contacts 40 and 4|. The intermittent opening and closing of the micro switch 25 is transmitted to an electrical counting means through the conventional leads 41.

It will be appreciated that the device illustra ed and described herein is but a preferred form of our invention and that it may take other forms without departing from the spirit of the invention as defined in the appended claims.

The invention claimed is:

1. In a measuring instrument the combination of a support, a traction wheel rotatably mounted on the support, a train of gears operatively connected to the traction wheel, a switch, contact means for the switch, and rockable means in engagement with the train of gears and actuated upon rotation of said traction wheel, said rockable means having an operative connection with said switch contact means.

2. In a measuring instrument the combination of a support, a traction wheel rotatably mounted on the support, a train of gears operatively connected to the traction wheel, a microswitch, contact means for the switch, a rockable shaft, means on the rockable shaft for actuating the switch contact means, and means for rocking the shaft actuated upon rotation of the traction wheel.

3. In a measuring instrument, a support, a traction wheel rotatably mounted on the support, a train of gears operatively connected to the traction wheel, a microswitch, contact means for the switch, a rockable shaft, means on the rockable shaft for actuating the switch contact means, a plurality of means for rocking the shaft actuated upon rotation of the traction wheel, each of said means being adapted to rock the shaft a different number of times for each rotation of the traction wheel, and means for rendering operative a selected one of the shaft rocking means.

4. In a measuring instrument, a support, a traction wheel rotatably mounted on the support, a train of gears operatively connected to the traction wheel, a microswitch, contact means for the switch, a rockable shaft, means on the rockable shaft for actuating the switch contact means, selectable means for rocking the shaft, each adapted to rock the shaft a different number of times per revolution, but all actuated upon rotation of the traction wheel, and means for selectively rendering operative one of the shaft rocking means.

5. In a measuring instrument, a support, a traction wheel rotatably mounted on the support, a train of gears operatively connected to the traction wheel, a microswitch, spring contact means for the switch, a rockable shaft, means on the rockable shaft for actuating the switch contact means, a rotatable shaft operatively connected with the train of gears, a plurality of means on the rotatable shaft each adapted to rock the rock shaft a different number of times per revolution of the traction wheel, and means for seletcively rendering operative one of the shaft rocking means.

6. In a measuring instrument, a support, a traction wheel rotatably mounted on the support, a train of gears operatively connected to the traction wheel, a microswitch, spring contact means for the switch, a rockable shaft, means on the rockable shaft for actuating the switch contact means, a rotatable shaft operatively connected with the train of gears, a star wheel on the rotatable shaft, and a pawl engageable with the star wheel operatively connected with said rockable shaft.

7. In a measuring instrument, a support, a traction wheel rotatably mountedon the support, a train of gears operatively connected to the traction wheel, a microswitch, spring contact means for the switch, a rockable shaft, means on the rockable shaft for actuating the switch contact means, a rotatable shaft operatively connected with the train of gears, a plurality of star wheels on the rotatable shaft each having a different number of teeth, and pawl means operatively connected to the rockable shaft selectively engageable with a particular one of the star wheels.

8. In a measuring instrument, a chambered handle member, a plate extending longitudinally within the handle, an arm extending from the handle, a traction wheel rotatably mounted on the arm, a train of gears supported artly on the arm and partly within the handle operatively connected with the traction wheel, a microswitch supported on the plate within the handle, spring contact means for the switch, a rockable shaft journaled in the plate, means on the rockable shaft for actuating the switch contact means, a rotatable shaft journaled in said plate, operatively connected to said train of gears, a plurality of star wheels fixed on the rotatable shaft each having a different number of teeth, a drum operatively connected to the rockable shaft, a plurality of pawls carried by said drum, and means for selectively positioning one of said pawls for engagement by one of said star wheels.

LELAND S. MALM. JOHN F. ONETO. 

